Single-atomic site catalysts for electrochemical nitrogen fixation

Figures & data

Figure 1. Possible reduction pathways in electrochemical nitrogen conversion, leading to a variety of nitrogen-containing species with different nitrogen oxidation states.

Figure 2. Multiple proposed N≡N cleavage and hydrogenation pathways in N₂ reduction.

Figure 3. Possible reduction pathways of NO_x conversion.

Table 1. Catalytic performances of SACs for ENRR and ENO_xRR.

Reactants	Central metal	Electrolyte	NH3 FE (%)	NH3 yield rate	References	Pontential (VRHE)
N2	Au	0.1 M HCL	12.3	2.32 μg h^−1 cm^−2	[101]	−0.2
N2	Au	5 mM H2SO4	11.1	72.5 μmol h^−1 mgcat^−1	[102]	−0.1
N2	Au	0.1 M Na2SO4	37.82	30.83 μg h^−1 mgcat^−1	[100]	−0.3
N2	Ag	0.1 M HCL	21.9	270.9 μg h^−1 mgcat^−1	[114]	−0.6
N2	Ru	0.05 M H2SO4	29.6	120.9 μg h^−1 mgcat^−1	[99]	−0.2
N2	Ru	0.1 M HCL	21	3.655 mg h^−1 mgRu^−1	[98]	−0.21
N2	Ru	0.5 M KOH	8.3	23 μg h^−1 mgcat^−1	[97]	0.05
N2	Fe	0.1 M KOH	56.55	7.48 μg h^−1 mgcat^−1	[106]	0
N2	Fe	0.05 M HCl	18.6	62.9 μg h^−1 mgcat^−1	[105]	−0.4
N2	Fe	0.5 M K2SO4	18.8	8.63 μg h^−1 mgcat^−1	[104]	−0.3
N2	Fe	0.1 m KOH	51	307.7 μg h^−1 mgcat^−1	[115]	−0.15
N2	Fe	0.1 M HCl	17.3	18.3 μg h^−1 mgcat^−1	[109]	−0.2
N2	Fe	0.1 M KCl	31.6	613 μg h^−1 mgcat^−1	[103]	−0.2
N2	Co	0.05 M Na2SO4	10.5	0.86 μmol h^−1 cm^−1	[116]	−0.2
N2	Mo	0.1 M KOH	14.6	34 μg h^−1 mgcat^−1	[110]	−0.3
N2	Mo	0.1 M KOH	13.27	37.67 μg h^−1 mgcat^−1	[111]	−0.4
N2	Mo	0.1 M Na2SO4	21	145.4 μg h^−1 mgcat^−1	[112]	−0.2 (SCE)
N2	Cu	0.1 M KOH	13.8	53.3 μg h^−1 mgcat^−1	[117]	−0.35
N2	Pd	0.05 M H2SO4	24.8	69.2 μg h^−1 mgcat^−1	[118]	−0.45
N2	Rh	9 mM H2SO4	73.3	271.8 μg h^−1 mgcat^−1	[119]	−0.3
N2	Nb	0.1 M HCL	10.4	209.4 μg h^−1 mgcat^−1	[120]	−0.8
NO3^−	Fe	0.1 M K2SO4 + 0.5 M KNO3	75	0.46 mmol h^−1 cm^−2	[121]	−0.66
NO3^−	Fe	0.1 M NaOH + 0.1 M Na2SO4 + 0.1 M NaNO3	98	0.03 mmol h^−1 cm^−2	[122]	−0.3
NO3^−	Fe	0.1 M KOH + 0.1 M KNO3	99.69	2.57 mol h^−1 gCat^−1	[123]	−0.5
NO3-	Cu	50 mg L^−1 NaNO3-N + 0.5 M NaSO4	94	9.23 mg h^−1 mgcat^−1	[124]	−1.5 (SCE)
NO3-	Cu	0.1 M KOH + 0.1 M KNO3	84.7	12.5 mol h^−1 gCu^−1	[43]	−1
NO3-	Rh	0.1 M Na2SO4 + 0.1 M KNO3	93	1.27 mmol h^−1 cm^−2	[125]	−0.2
NO3-	Au	0.1 M KOH + 7.4 mM KNO3	90.5	555 μg h^−1 cm^−2	[126]	−0.2
NO3-	Ru	1 M KOH + 1 M NaNO3	87.3	22.2 mol h^−1 gCat^−1	[42]	−0.3
NO3-	Cu	1 M KOH + 1 M KNO3	95.5	13.8 mol h^−1 gCat^−1	[44]	−1
NO3-	Cu	0.5 M Na2SO4 + 1000 ppm N-KNO3	88.46	28.73 mg h^−1 cm^−2	[45]	−2
NO	Nb	0.1 M HCL	77	8398 μg h^−1 mgcat^−1	[120]	−0.6

Figure 4. (a) Schematic illustration of synthetic procedure for Au_SA/np-MoSe₂. (b) NH₃ yield rates and (c) FE at different applied potentials. Copyright 2022, John Wiley and Sons [100]. (d) Scheme of the synthetic procedure for Ru SAs/N-C. (e) FE and (f) NH₃ yield rates at different applied potentials. Copyright 2018, John Wiley and Sons [99]. (g) FEs over Rh/MnO₂ in a dilute electrolyte and water-in-salt electrolytes. Copyright 2022, Elsevier [119].

Figure 5. (a) Transmission electron microscopy (TEM) image of Fe_SA-N-C. Scale bar, 50 nm. (b) The high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of Fe_SA-N-C. Scale bar, 2 nm. (c) NH₃ yield rates and FE at different applied potentials. (d) Surface-area-normalized NH₃ yield rate at different applied potentials on Fe_SA-N-C and N-C. Copyright 2019, Spring Nature [106]. (e) Schematic illustration of the synthetic process of Cu-N-C. (f) NH₃ FE at different applied potentials. (g) i–t curve. Copyright 2022, John Wiley and Sons [44]. (h) NH₃ yield rates and (i) FE at various applied potentials. Copyright 2021, Elsevier [129].

Figure 6. (a) Free-energy diagrams for ENRR on Mo/BCN through different reaction pathways. Copyright 2022, American Chemical Society [111]. (b) N₂-TPD curves of Co single-atom embedded N-doped porous carbon (CSA/NPC). Copyright 2019, Royal Society of Chemistry [116]. (c) Optimized Fe-(O-C₂)₄ configuration, N₂ adsorption at end-on and side-on and corresponding Bader charge distribution of *N₂ (yellow and blue represent charge accumulation and depletion, respectively). Copyright 2020, John Wiley and Sons [115]. (d) Pots of charge density difference. The red and dark blue regions represent electron density depletion and accumulation, respectively. Copyright 2022, John Wiley and Sons [42]. (e) Free-energy diagrams for HER over Fe-MoS₂ and MoS₂. Copyright 2020, John Wiley and Sons [104]. (f) Free-energy diagrams for ENO₃⁻RR on M-MoS₂ nanosheets. Copyright 2021, John Wiley and Sons [123]. (g) Structure for copper-porphyrin molecule with eight substituent groups. Copyright 2016, American Chemical Society [140]. (h) Schematic illustration of the catalyst depicted structure. Copyright 2022, American Chemical Society [141].

Figure 7. (a) Schematic illustration of ENRR for Cu-N_x structure. (b) Free-energy diagrams for the ENRR on Cu-N₂ through different reaction pathways. Copyright 2019, American Chemical Society [117]. Calculated free energies for (c) NO₃⁻ adsorption and (d) NO₂⁻ adsorption on Cu (111), Cu-N₄, and Cu-N₂ surfaces, respectively. The brown, grey, blue and red balls represent C, N, Cu and O atoms, respectively. Copyright 2020, John Wiley and Sons [149].

Qin Q, Heil T, Antonietti M, et al. Single-site gold catalysts on hierarchical N-doped porous noble carbon for enhanced electrochemical reduction of nitrogen. Small Methods. 2018;2(12):1800202.

 Web of Science ®Google Scholar

Wang X, Wang W, Qiao M, et al. Atomically dispersed Au1 catalyst towards efficient electrochemical synthesis of ammonia. Sci Bull. 2018;63(19):1246–1253.

 PubMed Web of Science ®Google Scholar

Chen D, Luo M, Ning S, et al. Single-atom gold isolated onto nanoporous MoSe2 for boosting electrochemical nitrogen reduction. Small. 2022;18(4):e2104043.

 PubMed Web of Science ®Google Scholar

Chen Y, Guo R, Peng X, et al. Highly productive electrosynthesis of ammonia by admolecule-targeting single Ag sites. ACS Nano. 2020;14(6):6938–6946.

 PubMed Web of Science ®Google Scholar

Geng Z, Liu Y, Kong X, et al. Achieving a record-high yield rate of 120.9 μgNH3 mgcat.-1 h-1 for N2 electrochemical reduction over Ru single-atom catalysts. Adv Mater. 2018;30(40):1870301.

 Web of Science ®Google Scholar

Tao H, Choi C, Ding L-X, et al. Nitrogen fixation by Ru single-atom electrocatalytic reduction. Chem. 2019;5(1):204–214.

 Web of Science ®Google Scholar

Yu B, Li H, White J, et al. Tuning the catalytic preference of ruthenium catalysts for nitrogen reduction by atomic dispersion. Adv Funct Mater. 2019;30(6):1905665.

 Web of Science ®Google Scholar

Wang M, Liu S, Qian T, et al. Over 56.55% faradaic efficiency of ambient ammonia synthesis enabled by positively shifting the reaction potential. Nat Commun. 2019;10(1):341.

 PubMedGoogle Scholar

Lü F, Zhao S, Guo R, et al. Nitrogen-coordinated single Fe sites for efficient electrocatalytic N2 fixation in neutral media. Nano Energy. 2019;61:420–427.

 Web of Science ®Google Scholar

Su H, Chen L, Chen Y, et al. Single atoms of iron on MoS2 nanosheets for N2 electroreduction into ammonia. Angew Chem Int Ed. 2020;59(46):20411–20416.

 PubMed Web of Science ®Google Scholar

Zhang S, Jin M, Shi T, et al. Electrocatalytically active Fe-(O-C2)4 single-atom sites for efficient reduction of nitrogen to ammonia. Angew Chem Int Ed. 2020;59(32):13423–13429.

 PubMed Web of Science ®Google Scholar

Chen J, Kang Y, Zhang W, et al. Lattice-confined single-atom Fe1Sx on mesoporous TiO2 for boosting ambient electrocatalytic N2 reduction reaction. Angew Chem Int Ed. 2022;61(27):e202203022.

 PubMed Web of Science ®Google Scholar

Li J, Chen S, Quan F, et al. Accelerated dinitrogen electroreduction to ammonia via interfacial polarization triggered by single-atom protrusions. Chem. 2020;6(4):885–901.

 Web of Science ®Google Scholar

Liu Y, Xu Q, Fan X, et al. Electrochemical reduction of N2 to ammonia on Co single atom embedded N-doped porous carbon under ambient conditions. J Mater Chem A. 2019;7(46):26358–26363.

 Web of Science ®Google Scholar

Han L, Liu X, Chen J, et al. Atomically dispersed molybdenum catalysts for efficient ambient nitrogen fixation. Angew Chem Int Ed. 2019;58(8):2321–2325.

 PubMed Web of Science ®Google Scholar

Shi L, Bi S, Qi Y, et al. Anchoring Mo single-atom sites on B/N codoped porous carbon nanotubes for electrochemical reduction of N2 to NH3. ACS Catal. 2022;12(13):7655–7663.

 Google Scholar

Hui L, Xue Y, Yu H, et al. Highly efficient and selective generation of ammonia and hydrogen on a graphdiyne-based catalyst. J Am Chem Soc. 2019;141(27):10677–10683.

 PubMed Web of Science ®Google Scholar

Zang W, Yang T, Zou H, et al. Copper single atoms anchored in porous nitrogen-doped carbon as efficient pH-universal catalysts for the nitrogen reduction reaction. ACS Catal. 2019;9(11):10166–10173.

 Web of Science ®Google Scholar

Han L, Ren Z, Ou P, et al. Modulating single-atom palladium sites with copper for enhanced ambient ammonia electrosynthesis. Angew Chem Int Ed. 2021;60(1):345–350.

 PubMed Web of Science ®Google Scholar

Shen P, Li X, Luo Y, et al. Ultra-efficient N2 electroreduction achieved over a rhodium single-atom catalyst (Rh1/MnO2) in water-in-salt electrolyte. Appl Catal B. 2022;316:121651.

 Web of Science ®Google Scholar

Wang J, Feng T, Chen J, et al. Electrocatalytic nitrate/nitrite reduction to ammonia synthesis using metal nanocatalysts and bio-inspired metalloenzymes. Nano Energy. 2021;86:106088.

 Web of Science ®Google Scholar

Wu ZY, Karamad M, Yong X, et al. Electrochemical ammonia synthesis via nitrate reduction on Fe single atom catalyst. Nat Commun. 2021;12(1):2870.

 PubMed Web of Science ®Google Scholar

Li P, Jin Z, Fang Z, et al. A single-site iron catalyst with preoccupied active centers that achieves selective ammonia electrosynthesis from nitrate. Energy Environ Sci. 2021;14(6):3522–3531.

 Web of Science ®Google Scholar

Li J, Zhang Y, Liu C, et al. 3.4% solar-to-ammonia efficiency from nitrate using Fe single atomic catalyst supported on MoS2 nanosheets. Adv Funct Mater. 2021;32(18):2108316.

 Web of Science ®Google Scholar

Chen H, Zhang C, Sheng L, et al. Copper single-atom catalyst as a high-performance electrocatalyst for nitrate-ammonium conversion. J Hazard Mater. 2022;434:128892.

 PubMed Web of Science ®Google Scholar

Yang J, Qi H, Li A, et al. Potential-driven restructuring of Cu single atoms to nanoparticles for boosting the electrochemical reduction of nitrate to ammonia. J Am Chem Soc. 2022;144(27):12062–12071.

 PubMed Web of Science ®Google Scholar

Liu H, Lang X, Zhu C, et al. Efficient electrochemical nitrate reduction to ammonia with copper-supported rhodium cluster and single-atom catalysts. Angew Chem Int Ed. 2022;61(23):e202202556.

 PubMed Web of Science ®Google Scholar

Zhang Y, Chen X, Wang W, et al. Electrocatalytic nitrate reduction to ammonia on defective Au1Cu (111) single-atom alloys. Appl Catal B. 2022;310:121346.

 Web of Science ®Google Scholar

Yao Y, Zhao L, Dai J, et al. Single atom Ru monolithic electrode for efficient chlorine evolution and nitrate reduction. Angew Chem Int Ed. 2022;61(41):e202208215.

 PubMed Web of Science ®Google Scholar

Xu M, Xie Q, Duan D, et al. Atomically dispersed Cu sites on dual-mesoporous N-doped carbon for efficient ammonia electrosynthesis from nitrate. ChemSusChem. 2022;15(11):e202200231.

 PubMed Web of Science ®Google Scholar

Cheng XF, He JH, Ji HQ, et al. Coordination symmetry breaking of single-atom catalysts for robust and efficient nitrate electroreduction to ammonia. Adv Mater. 2022;34(36):e2205767.

 PubMed Web of Science ®Google Scholar

Peng X, Mi Y, Bao H, et al. Ambient electrosynthesis of ammonia with efficient denitration. Nano Energy. 2020;78:105321.

 Web of Science ®Google Scholar

Weng Z, Jiang J, Wu Y, et al. Electrochemical CO2 reduction to hydrocarbons on a heterogeneous molecular Cu catalyst in aqueous solution. J Am Chem Soc. 2016;138(26):8076–8079.

 PubMed Web of Science ®Google Scholar

Qin J, Liu H, Zou P, et al. Altering ligand fields in single-atom sites through second-shell anion modulation boosts the oxygen reduction reaction. J Am Chem Soc. 2022;144(5):2197–2207.

 PubMed Web of Science ®Google Scholar

Zhu T, Chen Q, Liao P, et al. Single-atom Cu catalysts for enhanced electrocatalytic nitrate reduction with significant alleviation of nitrite production. Small. 2020;16(49):e2004526.

 PubMed Web of Science ®Google Scholar